Ultrasonic properties of V 2O 5[sbnd]P 2O 5 amorphous materials at different temperatures

Abstract

Investigations are reported of the acoustical properties of V2O5 P2O5 glass, on which other studies such as structural, spectroscopic, NMR and electrical conductivity have been reported in the literature. In the present investigation, the velocity and attenuation of longitudinal and transverse ultrasonic waves in four different compositions of (V2O5)x (P2O5)1−x glass system (x = 0.4769, 0.6020, 0.7487 and 0.8227) have been measured at temperatures ranging from 80 to 300 K with the help of an ultrasonic pulse echo apparatus operating at 8 MHz frequency. The velocity data have been used to find the elastic moduli and Debye temperature for each composition. The results indicate that for each composition the velocities decrease slowly and monotonically with increasing temperature and the attenuation as a function of temperature shows a broad peak which shifts to lower temperature as the V2O5 content increases. The temperature dependence of ultrasonic velocity and attenuation has been interpreted in terms of a thermally activated relaxation process which comes into play when the ultrasonic wave disturbs the equilibrium of an atom moving in a double-well potential in the glass network.